Temperature responsive switch



March 24, 1953 J. A. SENN 2,632,825

TEMPERATURE RESPONSIVE SWITCH Filed-Nov. 2l, 1949 di B INVENToR. 5e x aflm aam i 8| J U R E A 5 E N N l76A A 72A mmm 64 35 ATTRNEYEI PatentedMar. 24, 1953 UNITED TEMPERATURE RESPONSIVE SWITCH Jurg A. Senn,Milwaukee, Wis., assigner to Perfex Corporation, Milwaukee, Wis., acorporation of Wisconsinl Application November 21, 1949, Serial N0.128,552

11 Claims.

This invention concerns a type of temperature or pressure responsiveswitch which has for its main object the elimination of destructive4arcing or frying of the :contacts thru the utilization of a novellatching arrangement.

In the past there has been developed many arrangements for coping withthe destructive aroing resulting from slow make and break of contacts.Primarily, the def-ect is remedied by creating a swift or snap actionIto converge and separate the contacts. The over-center spring switchaction has proven somewhat successful but is characterized by therequirement that the cut-in and `cut-out points be set relativelyywidely apart, i. e. that the differential setting be relatively largeto insure proper Contact pressure, also these arrangementshave :a rangeof Vanishing contact pressure, for as the over-center spring is carriedover center, Ithe conta-ct pressure is momentarily reduced to zero. Forpurposes of precise and sensitive control some form of latchingarrangementhas been found to be more satisfactory.

lContactv arcing on contact separa-tion as such has no relation Ito thecontact pressure preceding this event. But persistent high contactpressure up to the point of. contactv separation keeps the resistance ofthe junction low'and therefore also the voltage drop. Thus less wattageis develope-d at this junction anda colder'contact is the result, whichin Iturn hasV .the effect of lreducing the thermal gradientv induced bythe subsequent arc on the contacts;

This invention concerns a type' of switch latching mechanism that botheiects a switch open and switch yclosed latching arrangement butk at thesame time' increases' the -contact pressure just vprior to attainingthese changed positions.

It is a further object of this invention to 'illusf trate a latchingarrangement thatis adaptable to many types of actuating mechanisms topro-w vide a versatile and economical control underr varied conditionsand requirements.

For .a more' complete understandingoff'the invention reference shouldnow be had t" the draw ing" in which, l

Fig. 1 isa side view ofone' embodiment' of' the device shown' in switch.closed positionju'st priorV to being latched open;

Fig. 2 is a side view of the device of` Fig. 1 with the switch shown inopen position;

Fig. 3 is a side view of a modification of Figs. 1 and 2;

Fig. 4; is a side view of a modification of Figs. 1, 2 and 3;

fiat spring hinge I2.

Fig. 5 is a sectional View taken :along linesV phr-agm assembly and IaU-shaped spring, theV device itself is of the reverse' acting type, i.e. it closes its contacts on a temperature rise. (In

Figs. 3, 4, 5 :and 6 the actuating element of the device consists of aU-shap'ed bimeta-l.

Referring now to Figs. 1 and 2, the device shown comprises an insulationbase 'IIJ having attachedv thereto a U-shaped structure Il by means of afThe spring hinge I2 is held .to the base I0 by a connector plate I3,washer Iil and screw I5. The spring hinge I2 is biased in a' downwarddirection to move the U-shaped structurel I ina counterclockwisedirection about the screw I-5. The structure II consists of -a U-shapedspring I6" attached to spring hinge I|2 by rivet I'I. .The U-shapedspring IB is biased to converge its ends. Between the leg-sof the U=shaped spring IIS is placed a sealed diaphragm I 8, having an upper.connecting rod lI B'secured -to the upper leg of spring |16k and a balljoint 20 secured to the lower leg of spring' I6, to control the positionof the legs of U-shaped spring I6. This diaphragm structure is a sealedunit having a duid iill subject to temperature changes to eiect movementof .the Varm I9 and ball 20. fIhis diaphragm unit is explained 'indetail in application 4Serial Number 600,862, 'lled June'22, 1945, now'Patent Number 2,487,947.

At the left sidov of the base lo another fiatspring hinge 22 is fastenedto the base and to al connectorV plate 23 by a washer 24 and a screw 25.The opposite' end of spring hinge 22 is fastened to a contact arm 26having a contact 21 for engagement with contact 2I which is" fastened tothe lower leg of 'spring I6. Spring hinge 22 is biased downwardly topivot contact arm' 26`in a clockwise direction about the screw 25. Aiso'fastened to spring 22 is an insulatiopiece 28. The'v -v spring 22,contact arm 26 and insulation piece '28 are' secured together by rivet29. Extending up= wardiy from" the pie-oo 2a is' o. latch 30 fastenedbyv rivet 3l. The insulation piece 2'8 electrically insulates theU-shaped spring I6 from the cntact circuit. The upper end of latch3'0engage's with the end 33 of U-shaped spring I6 to rain'- tain the U-shaped' spring I6 in 'the' position shown in2 Fig. 1, holdingV againstlthe bias of spiinghig'e Fastened tc the U-shaped spring" I6` by'rivetnI1 is a bracket 34 which supports a range adjusting screw 35. Thefunction of screw 35 is to spread and converge the projecting legs ofU-shaped spring I6 and thereby vary the operating or cut-in point of thedevice. There is also added in the base I6 a stop adjusting screw 36 topermit varying of the differential setting between the cut-in andcut-out points of the device. Two connecting screws 32 and 31 permitcircuit connections to be made for a circuit to be controlled.

In the operation as shown in Fig. 1, a temperature decrease affectingthe diaphragm I3 is reiiected in a converging action or the legs ofU-shaped spring I5 thru the force exerted by the spring bias of springI6. The leg 33, however, is restrained by the latch 39 from moving in adownward direction. The contact end 2i is free, however, and startsmoving upwardly away from the stop 36. The end 2l, which is already inengagement with contact 21, will thereby move contact 21 and contact arm26 upwardly. Fig. 1 shows this movement after a period of time haselapsed and the movement of contact end 2i has progressed from a pointof rest on the stop 36 to the position shown. The quiescent positionwhen contacts are closed has the portion of member I6 carrying Contact2l abutting the stop 36. Note, that as contact arm 25 moves upwardly,`the spring 22 resists this movement thereby causing increased contactpressure between contacts 21 and 2|. The downward bias of spring I2 is asomewhat negligible factor at this time because it acts on the wholeU-shaped structure I I which is not movable downwardly as a unit untilthe latch 30 releases the end 33. This is effected after a predetermineddistance has been traversed by arm 26 and latch 33 is kicked out fromunder end 33 of spring I6. Then the U-shaped structure II moving as aunit under the bias of spring hinge I2 snaps downward until arm I6 engages the stop 33. The contacts 2l and 21 snap open because latch arm 33and arm 26 remain in their raised positions, held by end 33 abuttinglatch arm 39. Note that the action or breaking contact is accomplishedat a point when contact pressure is at a maximum.

With the switch now in Ithe position as shown in Fig. 2 the reverseoperation will now be described. In this position (Fig. 2) end 33 actsas the latch to hold the latch arm 39 against clockwise movement underthe bias of spring 22. An increase in temperature will now result in anexpansion of the diaphragm I3 and the resulting spreading of the legs 33and I6 by the rod I9 and ball 29. But leg I6 and contact 2i are nowabutting the stop 36, therefore movement of leg I6 downward is blocked.Thus the spreading action of ythe diaphragm I3, arm I9 and ball 23 isreflected only in the upward movement of end 33. As end 33 movesupwardly the contact arm 26 and arm 39 are moved slightly in acounterclockwise direction since arm 39 is inclined slightly to theright as viewed in Figs. 1 and 2, this further increases the Itension ofspring 22. This action increases the bias of spring 22 in the clockwiseydirection but is not released until the latch 33 clears the latch arm39 and the contacts 21 and 2 I snap closed.

In Figs. 3 and 5 is shown a modification of Figs. 1 and 2 whereby aU-shaped bimetal is substituted as the actuating mechanism for thediaphragm I8 and spring II of Figs. l and 2 and the device itself hasthe conventional sequence of operation, i. e. it opens its contacts on atempera- Iture rise. In Figs. 3 and 5 the insulation base 31 has aU-shaped structure 38 pivotally attached thereto by a nat spring 39. Thespring 39 is attached to the base 31 by a washer 40 and a screw CII. Thebimetal 132 of the U-shaped structure 38 is secured to .the spring 39 bya rivet 43. The spring 39, like its counterpart in Figs. l and 2, springI2, is biased in a downward direction.

At the left end of the base 31, two connector plates M and 43A (Fig. 5),two flat springs 45 and 45A (Fig. 5), an insulation piece 46, dat spring41, and washer 43 are secured by screws 49 and 49A (not shown).

Note, that in Figs. 3, 4, 5 and 6 a contact bridge arrangement is usedto eliminate current flow thru the bimetals. This is necessary because,as is well known, current now and the resulting generation of heat aectsthe operation of thermostatic bimetal.

As shown in Figs. 3 and 5, the lower contact arms 50 and 59A areattached to flat springs 45 and 45A respectively by rivets 5I (one ofwhich is shown). The lower contact arms 56 and 59A are electricallyseparated but mechanically connected by an insulation bridge 52 whichallows for their synchronous movement. The upper contact arms 53 (one ofwhich is shown) are attached to flat spring 41. electrically andmechanically connects contacts 55 and 55A of contact arms 53. Thecontact bridge 55-5il-55A, engages with contacts 56 and 53A to completethe circuit traced as follows: connector 35, spring 45, contact arm 59,contact 56, contact 55, conductor 56, contact 55A, contact 56A, contactarm 53A, spring 45A and connector 55A. The contact arms 53 and 53A arejoined and fastened to spring 41 by rivets 51. Extending upwardly fromthe rivet 51 is an extended portion 53 of arms 53. This portion 53constitutes the latch for the end 59 of bimetal 42.

As can be seen in Fig. 5, the lower leg 69 of bimetal 32 coacts with theinsulation bridge 52 to move the lower contact arms 59 and 59A inaccordance with temperature changes affecting bimetal 42.

Attached to bimetal 42 by rivet 43 is a bracket 6I which serves as asupport for a range or operating point adjusting screw 62. The screw 62adjusts the operating point of the device by varying the distancebetween the bimetal legs 59 and 59 as does screw 35 in Figs. 1 and 2.

A stop adjusting screw 63 is provided to regulate the extremity oftravel of leg and thereby provides a differential adjustment.

In operation, ambient temperature changes affecting the bimetal 42 causethe legs 59 and 65 to ilex in opposite directions for any giventemperature change. By way of example, assuming -the fast expandingmetal component of member 33 is located on the outside an increase inthe temperature will cause leg 59 to flex downwardly and leg 5I) to flexupwardly. Leg 59 is restrained against downward movement by latch 53 butleg 65 will move upwardly engaging insulation bridge 52. Furthermovement of leg 60 will carry bridge 52 and contacts 56 and 56A upwardlypushing contacts 55 and 55A and their contact arms 53 upwardly. Thismovement will cause arms 53, and latch 58 to pivot counterclockwisearound the point 49 which after a predetermined distance will disengagelatch 5B from leg 59 causing the contacts to open with a snap. Thisoperation of the latch mechanism is the same as that previouslydescribed in connection with Figs. 1 and 2 except that in Figs. 3 and 5A conductor bridge 54 'a temperature increase causes the contacts toopen while in Figs. l and 2 a temperature decrease causes the contactsto open. Note that in the modification shown in Figs. 3 and 5 no part ofthe current will flow thru the bimetal 38 because no contacts aremounted on the bimetal.

In the modification shown in Figs. 4 and 6 a bimetal is again utilizedas the actuating element but the insulation and conduction bridges arereversed. The insulation base S4 has a flat spring S5 attached by awasher 66 and screw B1. A U- shaped bimetal 5S is fastened to the spring65 by a rivet @9. Also attached to the bimetal 68 by rivet 69 is abracket i8 supporting a range adjusting screw 'H similar to screws 35and 52 of Figs. l, 2 and 3.

The left side of insulation base 54 has two connectors 'l2 and 12A (Fig.6), two Lfiat springs I3 (one of which is shown) and two washers 74 (oneof which is shown) held by screws 'l5 (one of which is shown). To thespring 'i3 is fastened contact arm l5. To one of the springs 73 isfastened contact arm A (Fig. 6). Attached across springs 'i3 is aninsulation piece il held by rivets i8. Contact arms .'16 and 15A arefastened to contacts 'i9 and 79A (Fig. 6) respectively. These contacts,'i9 and 19A, are located physically adjacent to a contact bridgecomprised of contact 8%, conductor` 83A and contact SBB (Fig. 6). Thiscontact bridge is insulated from the bimetal leg Si by an insulationstrip S5.

Attached to the insulation piece 'Il by rivet S3 is a latch 2. The latch82, as shown, engages the bimetal leg 84. A stop adjusting screw 85periorins the same function as in Figs. l, 2, 3 and 5.

The operation of this modification (Figs. 4 and 6) is the same as `inFigs. 3 and 5 and therefore requires no further explanation. The contactstructure Si? in this mcdication is physically mounted on the bimetal 8ibut electrically insulated therefrom. The circuit to be controlled canbe connected across terminals 'i2 and 72A. The circuit through thedevice can be traced as follows: terminal l2, spring '13, contact armiii, contact i9, contact Sil, conductor 83A, contact 855B, Contact QA,contact arm SA, other spring 13 and terminal 72A.

From the foregoing description it will be readily apparent that manymodifications of this invention are possible and I wish to be limitedonly by the scope of the appended claims.

What is claimed is:

l. A condition responsive switching mechanism including a base. aU-shaped member in spaced overlying relation to said base, the legs ofsaid member being moveable relative to each other upon a conditionchange, a stop mounted on said base adjacent one leg of said U-shapedmember, first biasing means biasing said U -shaped member against saidstop, a first contact mounted for movement by said one leg, moveablemeans including a second contact engageable with said first contact anda latch member, said moveable means being moveable by said one leg froma iirst position wherein said latch member is in latching engagementwith the other leg or" said U- shaped member and said contacts areclosed to a second position wherein said contacts are open and saidlatching engagement is released, said other leg retaining said latchmember in said second position, second biasing means biasing saidmoveable means into said first position, said one leg being moveabletoward said other leg upon a change in said condition in one sense to.move

said moveable means from said first position to said second positionagainst the force exerted by said second biasing means, said other legbeing moveable upon a condition change in another sense to permit saidsecond biasing means to move said moveable means back to said firstposition, and adjusting'means for manually adjusting the relativeposition of the legs of said U-shaped member.

2. A temperature responsive switching mechanism including a base, aU-shaped member in spaced overlying relation to said base, an expansibletemperature responsive element mounted within the bight'ofsaid U-shapedmemberto provide relative movement between the legs of said member, anadjustable stop mounted .on said base adjacent one leg of said U-shapedmember, first biasing means biasing said U-shaped member against saidstop, a first contact mounted for movement by said one leg, moveablemeans including a second contactengageable withsaid iirst contact and alatch member,fsaid moveable means being moveable by said one leg from afirst position wherein said latch member is in latching engagement withthe other leg Iof said U- shaped member andsaidcontacts are closed to asecond position wherein said contacts are open and said latchingengagement .is reelased, said other leg retaining saidlatch member insaid second position, second biasing means biasing said moveable meansinto said first position, .said one legr being moveable toward saidother leg upon `a decrease in the temperature affecting vsaidtemperature responsive element to thereby move said moveable means fromsaid first position to said second position against the force exerted bysaid second biasing means, said other leg being moveable upon anincrease in said temperature to permit said second biasing means to movesaid moveable means back to said first position and adjusting means formanually adjusting the relative position of the legs of said U -shapedmember.

3. A temperature responsive switching mechanism including a base, aU-shaped bimetal member in spaced overlying relation to said base, an`adjustable stop mounted on said base adjacent one leg of said member,first biasing means biasing said member against said stop, a rst contactmounted for movement by said one leg, movable means including a secondcontact engageable with said first contact and a latch member, saidmovable means being moveable by said one leg from a first positionwherein said latch member is in latching engagement with the other legoi said member and said contacts are closed to a second position whereinsaid contacts are open. and said latching engagement is released, saidother leg retaining said latch member in said second position, secondbiasing means biasing said moveable means intosaid rst position, saidone leg being movable toward said other leg upon a decrease in thetemperature affecting said bimetal member to thereby move said moveablemeans from said first position tosaid rsecond position against the forceexerted by said second biasing means, said 'other leg being movableupc-n an increase in said temperature to permit said second biasingmeans to move said moveable means back to said iirst position.

Li. A temperature responsive switching mechanism including a base, aU-shaped bimetal member in spaced overlying relation to said base, anadjustable stop mounted on said base adjacent one .leg of said member,first biasing means biasing said member against said stop, a firstcontact mounted 'for movement by said one leg, moveable means includinga second contact engageable with said rst contact and a latch inember,said moveable means being moveable by said one leg from a rst positionwherein said latch member is in latching engagement with the other legof said member and said contacts are closed to a second position whereinsaid contacts are open and said latching engagement is released, saidother leg retaining said latch member in said second position, secondbiasing means biasing said moveable means into said rst position, saidone leg being moveable toward said other leg upon a decrease in thetemperature affecting said bimetal member to thereby move said movablemeans from said first position to said second position against the forceexerted by said second biasing mean, said other leg being movable uponan increase in said temperature to permit said second biasing means tomove said moveable means back to said first position, and adjustingmeans for manually moving said legs relative to each other.

5. In a condition responsive switch, an insulation base having mountedthereon at one end a iirst spring member, a U-shaped spring biased toconverge its extremities mounted on said nrst spring member and biasedthereby in one direction, a stop on said base adjacent the lower leg ofsaid U-shaped spring, a second spring member mounted on the other end ofsaid base, a latch lever mounted on said second spring member' biasedthereby in one direction and abutting the upper leg of said U-shapedspring, a movable contact arm mounted on said second spring member,adjusting means for manually adjusting the relative position of the legsof said U -shaped spring, a diaphragm assembly supported between theupper and lower legs of said U-shaped spring to move said legs relativeto each other, a first contact mounted on the lower leg of said U-shaped spring for engagement with a second contact on said contact armwhereby converging movement of said diaphragm assembly causes said lowerleg to move upwardly carrying said contact and said contact arm upwardlyuntil said lever slips out from under said upper leg causing saidcontacts to open, and whereby diverging movement of said diaphragmassembly causes said upper leg to move upwardly until said upper legreleases said lever allowing the contact arm to spring downwardlyclosing the contacts.

6. In a condition responsive switch, an insulation base supporting aswitch structure comprising, a first spring member biased in onedirectio-n, a second spring member biased in said one direction, aU-shaped spring member biased to converge its ends, a lever attached tosaid second spring member having a latch member abutting one end of saidU-shaped spring member, adjusting means for manually -adjusting therelative position of the ends of said U-shaped spring member, a contactarm attached to said second spring member, a diaphragm structureoperatively connected to said vU-shaped spring member to diverge itsends under the inuence of condition changes, a stop on said baseadjacent one of the legs of said U-shaped spring member, a contactmounted on said U -shaped spring member for engagement with said contactarm whereby converging action of said U-shaped spring results in anupward movement of said contact and a pivotal movement of said contactarm and said lever, whereby said latch member disengages said U-shapedspring member to snap open said contact and said contact arm, andwhereby diverging action of said U-shaped spring results in releasingsaid latch member to snap closed said contact and said contact arm.

'7. A temperature responsive switching mechanism including a. base, aU-shaped bimetal member in spaced overlying relation to said base, anadjustable stop mounted on said base adjacent one leg of said member,rst biasing means biasing said member against said stop, a rst contactmovable by said one leg, movable means on said base including a secondcontact engageable with said first contact and a latch member, saidmovable means being movable by said one leg from a first positionwherein said latch member is in latching engagement with the other legof said member and said contacts are closed to a second position whereinsaid contacts are open and said latching engagement is released, saidother leg retaining said latch member in said second position, secondbiasing means biasing said movable means into said first position, thirdbiasing means biasing said first contact against said one leg, said oneleg being movable toward said other leg upon a decrease in thetemperature affecting said bimetal member to thereby move said movablemeans from said rst position to said second position against the forceexerted by said second and third biasing means, said other leg beingmovable upon an increase in said temperature to permit said secondbiasing means to move said movable means back to said first position.

8. A temperature responsive switching mechanism including a base, aU-shaped bimetal member pivotally mounted on said base and biased in onedirection, a first contact pivotally mounted on said base, movable meanspivotally mounted on said base and biased in one direction, said movablemeans including a second contact engageable with said rst contact and alatch member, said latch member engageable with one leg of said U-shapedbimetal member, said contacts movable by the other leg of said U-shapedbimetal to effect contact action to a first latching position, and saidcontacts movable to a second position by reversed action of saidU-shaped bimetal to effect contact action to a second latching position.

9. In a temperature responsive device', an insulation base havingmounted thereon va U- shaped bimetal in spaced overlying relation tosaid base, a flrst biasing means biasing said bimetal against said base,a first contact mounted on said one leg and movable therewith, movablemeans carrying a second contact, second biasing means biasing saidmovable means against said rst contact, a latch member mounted on saidmovable means and engageable with the other leg of said U-shapedbimetal, and adjusting means for manually adjusting the relativeposition of the legs of said U-shaped bimetal.

10. A condition responsive switching mechanism including a base, aU-shaped member in spaced overlying relation to said base, the legs ofsaid member being movable relative to each other upon a conditionchange, rst biasing means biasing said U-shaped member against saidbase, a nrst contact mounted for movement by one leg of said U-shapedmember, movable means including a second contact engageable with saidfirst contact and a latch member, said movable means being movable bysaid one leg from a rst position wherein said latch member is inlatching engagement with the other leg of said U- shaped member and saidcontacts are closed to a second position wherein said contacts are openand said latching engagement is released, said other leg retaining saidlatch member in said second position, second biasing means biasing saidmovable means into said first position, said one leg being movabletoward said other leg upon a change in said condition in one sense tomove said movable means from said first position to said second positionagainst the force exerted by said second biasing means, said other legbeing movable upon a condition change in another sense to permit saidsecond biasing means to move said movable means back to said rstposition, and adjusting means for manually adjusting the relativeposition of the legs of said U- shaped member.

11. A condition responsive switching mechanism comprising a base, meansincluding a condition responsive element mounted in spaced overlyingrelation to said base, a spring biasing said means toward said base, acontact-carrying lever pivotally mounted on said base, a member carriedby said lever in engagement with a portion of said means when said leveris in a rst position and held in latching engagement by said spring,said means, upon a change in the condition moving said lever to a secondposition and into latching relation with said member for retaining saidlever in said second position, and contacts one of which is moved bysaid lever another being moved by said means. said contacts being closedwhen said lever is in said first position and open when said lever is insaid second position, and adjusting means for adjusting the magnitude ofthe condition change required to move said lever from said rst to saidsecond position.

JU'RG A. SENN.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,728,785 Claytor Sept. 17, 19292,969,625 Rich Feb. 2, 1937 2,146,608 Welle Feb. 7, 1939

